/// <summary>Converts the MIDI sequence into a new one with the desired format.</summary>
/// <param name="sequence">The sequence to be converted.</param>
/// <param name="format">The format to which we want to convert the sequence.</param>
/// <param name="options">Options used when doing the conversion.</param>
/// <param name="newResolution">the new resolution (disable using 0 or -1)</param>
/// <returns>The new, converted sequence.</returns>
/// <remarks>This is based on the excellent MidiSharp package by Stephen Toub.</remarks>
public static Sequence Convert(this Sequence sequence, int format, FormatConversionOption options, int newResolution, string trackName)
{
if (sequence.MidiFileType == format)
{
// If the desired format is the same as the original, just return a copy.
// No transformation is necessary.
sequence = new Sequence(sequence);
}
else if (format != 0 || sequence.Tracks.Count == 1)
{
// If the desired format is is not 0 or there's only one track, just copy the sequence with a different format number.
// If it's not zero, then multiple tracks are acceptable, so no transformation is necessary.
// Or if there's only one track, then there's no possible transformation to be done.
var newSequence = new Sequence(sequence.DivisionType, sequence.Resolution, 0, format);
foreach (Track t in sequence.Tracks)
{
newSequence.Tracks.Add(new Track(t));
}
sequence = newSequence;
}
else
{
// Now the harder cases, converting to format 0. We need to combine all tracks into 1,
// as format 0 requires that there only be a single track with all of the events for the song.
int originalResolution = sequence.Resolution;
if (newResolution <= 0)
{
newResolution = originalResolution;
}
sequence = new Sequence(sequence);
sequence.MidiFileType = (int)MidiHelper.MidiFormat.SingleTrack;
// Add all events to new track (except for end of track markers and SequenceOrTrackName events)
int trackNumber = 0;
var newTrack = new Track();
foreach (Track track in sequence.Tracks)
{
foreach (MidiEvent midiEvent in track.Events)
{
bool doAddEvent = true;
var msg = midiEvent.Message;
// check if this is a meta message
var mm = msg as MetaMessage;
if (mm != null)
{
// we have a meta message
// add all meta messages except the end of track markers (we'll add our own)
int type = mm.GetMetaMessageType();
if (type == (int)MidiHelper.MetaEventType.EndOfTrack)
{
doAddEvent = false;
}
else if (type == (int)MidiHelper.MetaEventType.SequenceOrTrackName)
{
doAddEvent = false;
// store track name, will be used later
if (string.IsNullOrEmpty(trackName))
{
byte[] data = mm.GetMetaMessageData();
string text = MidiHelper.GetString(data);
trackName = MidiHelper.TextString(text);
}
}
}
// check if this is a short message
var sm = msg as ShortMessage;
if (sm != null)
{
// get the data
var channel = sm.GetChannel();
var cmd = sm.GetCommand();
var data1 = sm.GetData1();
var data2 = sm.GetData2();
// If this event has a channel, and if we're storing tracks as channels, copy to it
if ((options & FormatConversionOption.CopyTrackToChannel) > 0 &&
trackNumber >= MidiHelper.MIN_CHANNEL && trackNumber <= MidiHelper.MAX_CHANNEL)
{
if (sm.IsChannelMessage())
{
// store the track number as the channel
sm.SetMessage(cmd, trackNumber, data1, data2);
}
}
if ((options & FormatConversionOption.NoteOffZero2NoteOnZero) > 0)
{
// If the event is a NoteOff with Volume 0
if (cmd == (int)MidiHelper.MidiEventType.NoteOff && data2 == 0)
{
// convert to a NoteOn instead
sm.SetMessage((int)MidiHelper.MidiEventType.NoteOn, channel, data1, data2);
}
}
}
// convert ticks if resolution has changed
if (originalResolution != newResolution)
{
if (midiEvent.Tick != 0)
{
double fraction = (double)midiEvent.Tick / (double)originalResolution;
int tick = (int)(fraction * newResolution);
midiEvent.Tick = tick;
}
}
// Add all events, except for end of track markers (we'll add our own)
if (doAddEvent)
{
//newTrack.Events.Add(midiEvent); // add to end of list
newTrack.Add(midiEvent); // add in the right position based on the tick
}
}
trackNumber++;
}
if (originalResolution != newResolution)
{
sequence.Resolution = newResolution;
}
// Sort the events by total time
// newTrack.Events.Sort((x, y) => x.Tick.CompareTo(y.Tick));
// Note! using newTrack.Add instead of newTrack.Events.Add, already ensures a correct sort order
// Top things off with an end-of-track marker.
newTrack.Add(MetaEvent.CreateMetaEvent("EndOfTrack", "", newTrack.Ticks(), 0));
// add a new track name as the very first event
newTrack.Events.Insert(0, MetaEvent.CreateMetaEvent((int)MidiHelper.MetaEventType.SequenceOrTrackName, trackName, 0, 0));
// We now have all of the combined events in newTrack. Clear out the sequence, replacing all the tracks
// with this new one.
sequence.Tracks.Clear();
sequence.Tracks.Add(newTrack);
}
return(sequence);
}
